THE PUTATIVE HEPARIN-SPECIFIC N-ACETYLGLUCOSAMINYL N-DEACETYLASE N-SULFOTRANSFERASE ALSO OCCURS IN NON-HEPARIN-PRODUCING CELLS/

N-Deacetylation and N-sulfation of N-acetylglucosamine of heparin and heparan sulfate are hypothesized to be mediated by different tissue-sp ecific N-acetylglucosaminyl N-deacetylases/N-sulfotransferases, which in turn lead to the higher L-iduronic acid and sulfate content of hepa rin versus heparan sulfate. Furthermore, the putative heparin-specific N-acetylglucosaminyl N-deacetylase/N-sulfotransferase has been report ed to require auxiliary proteins for its N-acetylglucosaminyl N-deacet ylase activity in vivo based on its requirement of polycations in vitr o, me have now found that cells derived from embryonic bovine trachea, a tissue that does not synthesize heparin, has a N-acetylglucosaminyl N-deacetylase/N-sulfotransferase, which has 95% amino acid sequence i dentity to the above enzyme postulated to be involved in the biosynthe sis of heparin. Both enzymes also have very similar affinity for their substrates, The trachea enzyme does not require additional effecters for its N-acetylglucosaminyl N-deacetylase activity in vitro even thou gh its biochemical characteristics are virtually the same as the enzym e previously isolated from cells of a heparin-producing mastocytoma tu mor. The trachea enzyme, which is encoded by an abundant 4.6-kilobase mRNA, like mastocytoma cells, has 70% amino acid sequence identity wit h the corresponding enzyme from rat liver postulated to participate in the biosynthesis of heparan sulfate. Heparan sulfate synthesized by t rachea cells has a higher content of sulfated iduronic acid than from other tissues, Together, the above results strongly suggest that the a bove enzymes from mastocytoma, liver, and trachea, per se, are not sol ely responsible for the selective tissue-specific synthesis of heparin or heparan sulfate; more likely cellular factors, additional enzymes, and availability of substrates in the Golgi lumen also play important roles in the differential synthesis of the above proteoglycans.